C++ 逐行拆分字符串
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C++ split string by line
提问by wangzhiju
I need to split string by line. I used to do in the following way:
我需要逐行拆分字符串。我以前是这样做的：
int doSegment(char *sentence, int segNum)
{
assert(pSegmenter != NULL);
Logger &log = Logger::getLogger();
char delims[] = "\n";
char *line = NULL;
if (sentence != NULL)
{
line = strtok(sentence, delims);
while(line != NULL)
{
cout << line << endl;
line = strtok(NULL, delims);
}
}
else
{
log.error("....");
}
return 0;
}
I input "we are one.\nyes we are." and invoke the doSegment method. But when i debugging, i found the sentence parameter is "we are one.\\nyes we are", and the split failed. Can somebody tell me why this happened and what should i do. Is there anyway else i can use to split string in C++. thanks !
我输入“我们是一体的。\不，我们是。” 并调用 doSegment 方法。但是当我调试时，我发现句子参数是“we are one.\\nyes we are”，并且拆分失败。有人可以告诉我为什么会发生这种情况，我应该怎么做。无论如何我可以用来在C++中分割字符串。谢谢 ！
回答by billz
I'd like to use std::getline or std::string::find to go through the string. below code demonstrates getline function
我想使用 std::getline 或 std::string::find 来遍历字符串。下面的代码演示了 getline 函数
int doSegment(char *sentence)
{
std::stringstream ss(sentence);
std::string to;
if (sentence != NULL)
{
while(std::getline(ss,to,'\n')){
cout << to <<endl;
}
}
return 0;
}
回答by Some programmer dude
You can call std::string::findin a loop and the use std::string::substr.
您可以std::string::find在循环中调用并使用std::string::substr.
std::vector<std::string> split_string(const std::string& str,
const std::string& delimiter)
{
std::vector<std::string> strings;
std::string::size_type pos = 0;
std::string::size_type prev = 0;
while ((pos = str.find(delimiter, prev)) != std::string::npos)
{
strings.push_back(str.substr(prev, pos - prev));
prev = pos + 1;
}
// To get the last substring (or only, if delimiter is not found)
strings.push_back(str.substr(prev));
return strings;
}
See example here.
请参阅此处的示例。
回答by Oleksandr Kozlov
std::vector<std::string> split_string_by_newline(const std::string& str)
{
auto result = std::vector<std::string>{};
auto ss = std::stringstream{str};
for (std::string line; std::getline(ss, line, '\n');)
result.push_back(line);
return result;
}
回答by Scourge
#include <iostream>
#include <string>
#include <regex>
#include <algorithm>
#include <iterator>
using namespace std;
vector<string> splitter(string in_pattern, string& content){
vector<string> split_content;
regex pattern(in_pattern);
copy( sregex_token_iterator(content.begin(), content.end(), pattern, -1),
sregex_token_iterator(),back_inserter(split_content));
return split_content;
}
int main()
{
string sentence = "This is the first line\n";
sentence += "This is the second line\n";
sentence += "This is the third line\n";
vector<string> lines = splitter(R"(\n)", sentence);
for (string line: lines){cout << line << endl;}
}
// 1) We have a string with multiple lines
// 2) we split those into an array (vector)
// 3) We print out those elements in a for loop
// My Background. . .
// github.com/Radicalware
// Radicalware.net
// https://www.youtube.com/channel/UCivwmYxoOdDT3GmDnD0CfQA/playlists
回答by Jelle Bleeker
This fairly inefficient way just loops through the string until it encounters an \n newline escape character. It then creates a substring and adds it to a vector.
这种相当低效的方式只是遍历字符串，直到遇到 \n 换行符。然后它创建一个子字符串并将其添加到一个向量中。
std::vector<std::string> Loader::StringToLines(std::string string)
{
std::vector<std::string> result;
std::string temp;
int markbegin = 0;
int markend = 0;
for (int i = 0; i < string.length(); ++i) {
if (string[i] == '\n') {
markend = i;
result.push_back(string.substr(markbegin, markend - markbegin));
markbegin = (i + 1);
}
}
return result;
}
